The goal of virtual reality is to fully or partially immerse a human in a visually coupled environment. By tracking the position and orientation of the user with sensors designed for this purpose and by coupling these measurements with a high-performance computer graphics system, we can generate a computer-synthesized view of a virtual environment that responds to the user's movements. Thus, the user does not just see a visual display on a terminal but is immersed within the display. Vr also allows natural real-time interaction with the ve. Instead of a gui, the system uses perceptual and multi-modal interfaces (such as gesture, audio, and speech recognition) to interact with the data. Natural locomotion devices let the user navigate through the ve. Also, because of the size of the typical projection-based vr display (caves and workbenches), groups of scientists and engineers can more easily work together to interpret data, making full use of the 3d portrayal.